Tabby's Star

A bizarre cosmic object known as "Tabby's star" exhibits strange dips in brightness, and scientists can't seem to figure out exactly why.

The star — also known as Boyajian's star or KIC 8462852 — is located 1,500 light-years from Earth. It has generated quite a bit of intrigue and speculation since 2015, when data from NASA's Kepler space telescope revealed that the star had an irregular cycle of brightness. In fact, data from 2011 and 2013 showed that the star dimmed by as much as 22 percent for days at a time.
"This [dimming] behavior was not something we were looking for or had trained our algorithms to find," Tabetha Boyajian, an assistant professor of astrophysics at Louisiana State University who led the team that first detected the star's fluctuations, said in a statement from NASA.

Scientists have tried to explain the star's weird behavior with hypotheses ranging from swarms of comets to alien megastructures. Here's a rundown of NASA's possible explanations.

Surrounded by dust

Photo Credit: NASA/Ames Research Center/Daniel Rutter

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Surrounded by dust

Recent studies have shown that the unusual dips in the object's brightness are likely caused by dust surrounding the star. New data from NASA's Spitzer and Swift space telescopes revealed that the star's dimming was more pronounced in ultraviolet than infrared light, suggesting that any particles surrounding the star could not be any larger than a dust grain (which infrared radiation can penetrate). Otherwise, the dimming would appear uniform across all wavelengths, astronomers have said.

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Ringed planet & asteroid clusters

Photo Credit: NASA/Ames Research Center/Daniel Rutter

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Ringed planet & asteroid clusters

Another study has suggested that a ringed planet and clusters of asteroids orbit the star, causing the strange dimming behavior. In fact, monitoring a star's changing brightness as seen from Earth is a common technique (called the transit method) for detecting exoplanets. In theory, when a planet passes in front of its parent star, observers on Earth would see a temporary dip in brightness.

However, scientists have said that the dips in brightness seen from Tabby's star are far too substantial to be caused by an orbiting planet.

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Ravenous star

Photo Credit: NASA/Ames Research Center/Daniel Rutter

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Ravenous star

One other possible explanation for the dramatic change in brightness is that Tabby's star is tearing apart and swallowing a planet. A similar behavior has been seen in some stars that have given birth to Earth-like rocky planets only to devour them later.

Scientists have developed a method for detecting planet-eating stars using their chemical signature. When a rocky planet plunges into a star, it leaves traces of particular elements, which absorb light in different ways. By looking at the wavelengths of light or spectra of a star, scientists can determine the abundance of certain elements that star contains and determine whether it gobbled up a planet.

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Swarm of comets

Photo Credit: NASA/Ames Research Center/Daniel Rutter

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Author Bio

Samantha Mathewson, Space.com Contributor

Samantha Mathewson joined Space.com as an intern in the summer of 2016. She received a B.A. in Journalism and Environmental Science at the University of New Haven, in Connecticut. Previously, her work has been published in Nature World News. When not writing or reading about science, Samantha enjoys traveling to new places and taking photos! You can follow her on Twitter @Sam_Ashley13.